Fluid transmission



July 28, 1936. R, M, @T15 2,049,078

FLUID TRANSMISSION Filed July 9, 1954 2 Sheets-Sheet 1 July 28, 1936. R. M OTlS 2,049,078

FLUID TRANSMISSION Filed July 9, 1934 2 Sheets-Sheet 2 Patented July 28, 1936 STAT irs

FLUID TRANSNHSSON Russell M. Otis, Pasadena, Calif.,

Burt-Warner Calif.

Power Corporation,

assignor to Pasadena,

Application `iuly 9, 1934, Serial bla/734,329

Claims.

My invention relates to fluid transmissions and particularly to closed circuit fluid transmission systems in which provision is made for braking of the driven member and in which a make-up 5 means is provided to inject new uid into the system to compensate for leakage.

An object of my invention is to make possible braking by the driving motor with consequent exhaustion of the main capacity of the low pressure side of the system without making it necessary for the make-up device to operate to inject new iluid into the system during this temporary depletion. Another object is to provide an arrangement of ports whereby the make-up l5 device will come into use when there is a legitimate need for more iiuid to be injected into the system. Other objects will appear from the disclosures in the specifications and drawings.

Fig. 1 is a drawing showing the fluid transmission as applied in an automobile.

Fig. 2 is a detail of the fluid make-up apparatus.

Fig. 3 is a detail of the uid motor.

In the application to an automobile, illustrated in Fig. 1, an internal combustion engine I mounted on frame I1 drives compressor 2 also mounted on frame I1 which draws fluid through intake pipe 3 and its associated compressor check valve and compresses it into high pressure reservoir 4 through pipe 5 and its associated compressor check valve. The high pressure iiuid passes through pipes 6 and 1, throttle 8, and pipe 9 to the valve-controlled iiuid motor III, which drives the wheels II. The fluid is exhausted from the motor I0 through pipe I2, to which is connected low pressure reservoir I3. When the compressor is compressing, it takes air 'out of pipe I2 through check valve I4, pipe I5, unloader valve I6 and pipe 3.*

4o The path of the uid is thus seen to be through a closed circuit to which are connected on both the high and the low pressure sides reservoirs which serve to prevent any sudden changes in pressure. The engine supplies the power to the 45 compressor which is used to pump iiuid, usually air, into the high pressure reservoir where the used energy is stored as potential energy of the iiuid. This energy is available for driving the uid motor which again transforms it into me- 50 chanical energy at the wheels. The closed circuit in a fluid transmission is particularly advantageous because of the huge outputs of power that can be trans 'tted with relatively small equipment, especially when the ratio of the pres- 55 sures on the high and low pressure sides of the (Cl. Gli-62) system is made about 3. Another advantage resides in the fact that, since the compression ratio is small, the temperature of the discharged air from the compressor is also low, and for the same reason, there is no freezing at the exhaust 5 of the uid motor.

For best emciency it is desirable to maintain the iiuid pressure in the high pressure side of the system substantially constant. To this end the speed of the internal combustion engine is 10 varied to correspond to the demand for fluid and when the speed is reduced to a little above the stalling speed the compressor is unloaded. Fluid pressure reaches diaphragm pressure regulator I8 by way of pipes 6 and I9 from high l5 pressure reservoir 4. The regulator I8 causes rod 20 to move in a direction to gradually close throttle 2I of carburetor 22 through linkwork 23 when the pressure in reservoir 4increases. The eiect of this is to decrease the speed of the en- 20 gineand compressor and decrease the amount of fluid pumped into the reservoir as pressure increases. When a pressure is reached at which a speed near to stalling occurs, the rod 20 is advanced to a point where the valve I6 is closed, 25 shutting oiI the intake supply to the compressor 2 which normally would be through pipe 3, valve I6, pipe I5, check valve I4, and pipe I2 from reservoir I3. After the intake is shut off, the compressor does no work and the engine idles'. 30 This condition persists until the pressure in reservoir 4 drops suiiiciently to permit the valve I6 andthe throttle 2I to open whereupon pumping again starts. If, for any reason,- the pressure regulation fails and the pressure exceeds the safe 35 limit, it is discharged from the high pressure reservoir 4 through pipe 6, the safety relief valve 24, pipe 26, and pipe I2 into the low .pressure reservoir I3.

In order to make upior leaks ofuid from the system into the atmosphere, an automatic make-up means is provided. This can be seen in detail by referring to Fig. 2. A compressor 26 is motmted on the frame I1 and has a shaft which is coupled to the shaft of engine l so that the compresser runs whenever the engine runs. 21 is the intake pipe and 28 is the discharge pipe. In the particular embodiment illustrated, air is employed as the working iiuid, so in the operation of the make-up means, when more air is demanded by the system, air is taken into' the compressor '26 through cleaner 29, pipe 30, valve 3|, pipe 21 and its associated compressor check valve and discharged through pipe 28 and its associated l compressor check valve-and pipe 32 into pipe I5 5.5

where it can be taken in by compressor 2 and pumped up into the high pressure side of the system. The air cannot, however, pass from pipe I5 back into the low pressure reservoir I3 because of the check valve I4 which permits fluid to pass only in a direction away from pipe I2.

The operation of the make-up system is automatically controlled. When the pressure in pipe I5 exceeds a predetermined value, it acts through pipe 32 on diaphragm regulator 33 to close valve 3| which shuts oil' the intake to the compressor 26, unloading it and causing it to stop discharging air into pipe I5. In the operation of the regulator 33, pressure acts on diaphragm 34 against the compression of spring 35, the reaction of which is taken by the bracket 36 mounted on the frame I 1, to move the rod 31 through packing 38 in a direction to bring the valve cone 33 against the valve seat 40. Should the pressure regulator 33 not function properly and the pressure in pipes I5, 32, and 28 rise to a dangerously high value, the safety valve 4I opens and passes iluid out through pipe 42 to the atmosphere.

'Ihe control of the motion of the car is through two levers: lever 43 which controls throttle 8 in the high pressure line to the fluid motor I0, and lever 44- which, through linkwork 45, controls 'the valves of motor I0. The iluid motor I0 is like an ordinary steam engine having cylinder 46, piston 41 onpiston rod 43, driving crank 50 through connecting rod 49. Crank 50 is on axle 5I attached to wheels II. The valve mechanism 52 controls the time of cut-01T, admission and exhaust and, in addition to being reversible, is capable of variation over a wide range of cut-od. 'I'he valve events are, of course, determined by the phase relation of valve 53 with respect to piston 41, which relation is; changed by manipulation of the mechanism 52 through movement of the lever 44. A standard Stephenson link has been shown and since this valve gear is so old and so well known to those skilled in the art, it is not considered necessary to explain its operation in detail.

In the normal operation of the car in the forward direction, uid pressures in the high and low pressure reservoirs stay substantially constant. The throttle 8 is` wide open; the valves of the uid motor are set in the forward position with the desired cut-off; the fluid passes from the high pressure side of the system through the iluid motor to the low pressure side from which it is compressed into the high pressure side again by compressor 2. The compressor speed variesand the compression starts and stops in response to the pressure in the reservoir 4. The compressor 26 compresses and idles at intervals depending upon the need for make-up fluid as shown by the pressure in pipe I5.

One of the most important advantages of the type of transmission here described is that it can be employed as a brake for the vehicle which it drives. 'I'his is accomplished by setting the valves of the motor in reverse which makes a compressor of the motor. Under these circumstances fluid is taken from low pressure reservoir I3 through pipe I2 into the motor I0 and is compressed and sent out through pipe 9. The energy required for the compression is supplied by the car in coming to rest. If the throttle 8 were left open during the braking operation, the car would immediately start backwards upon coming to rest, since the valves would be in reverse. Hence it is necessary to close the throttle during braking to provide a path from pipe 9 into -combination of means automatically injecting pressure reservoir and the intake pipe of said 3. But it is also necessarythe high pressure reservoir 4 and this path must not be conducting in the other direction. A check valve 54 in pipe 55 is, therefore, made to shunt the throttle l. This check valve permits fluid to be pumped by motor I0 into the tank 4; but when the car has stopped, the :duid cannot return to the motor to propel the car in the reverse direction.

During braking, iluid is taken from the low pressure reservoir I3 and is pumped into the l( high pressure tank by motor I0. To prevent the lowering pressure in the tank I3 from causing the make-up apparatus to start working, the check valve I4 is placed in the pipe I5 between the low pressure reservoir and the pipe 32 leadl5 ing to the make-up regulator 33 and the inlet to the compressor 2. This check valve I4 permits fluid to pass in the direction of the indicating arrow from the tank I3 and the pipe I2 into the pipe I5 and thence into the compressor intake and 20 into the make-up regulator; so when the car is being driven by the transmission the fluid can circulate freely and if there is a. real demand for more air in the system as evidenced by lowered pressure in the tank I3 it will quickly become ap- 25 parent in pipe I5 when the compressor 2 starts working. When, however, the pressure in tank I3 is lowered not by leakage of uid to the atmosphere but by having iiuid pumped out of it in the braking process, the pressure in pipe I5 remains 30 the same and, hence, there is no tendency for the make-up regulator to cause new air to be pumped into the system.

It is sometimes desirable to enlarge pipe I5 into a larger chamber as at 56 in order to make 35 somewhat more constant the pressure in the pipe I5. Of course, chamber 56 may be simply a section of tank I3 with check valve I4 between the two sections.

What I claim as new and desire to secure by 40 Letters Patent is:

1. In a closed pressure iluid transmission circuit including a compressor, a high pressure reservoir connected to the exhaust of said compressor, a reversible-valve iiuid motor having an intake adapted to be connected to said high pressure reservoir, a low pressure reservoir connected 'to the exhaust of said iiuid motor and adapted to be connected to the intake of said compressor, the

50 fluid into the low pressure side of the circuit when the pressure in the intake pipe of said compressor is lower than a predetermined value, and .valve means located in said circuit between said low 55 compressor and adapted to prevent a lowered pressure in the low pressure reservoir from being communicated to the compressor intake pipe to start the automatic injecting means.

2. In a closed pressure uid transmission cir- 60 cuit including a compressor, a high pressure reservoir connected to the exhaust of said compressor,

a reversible-valve fluid motor having an intake adapted to be connected to said high pressure reservoir, a low pressure reservoir connected to 65 fthe exhaust of said uid motor and adapted to be connected to the intake of said compressor, the combination oi' means automatically injecting iluid into the low pressure side oi the circuit in fluid to ow only in a direction from said low pressure reservoir toward said point.

3. In a closed pressure fluid transmission circuit including a compressor, a high pressure reservoir connected to the exhaustl of said compressor, a reversible-valve fluid motor having an intake adapted to be connected to said high pressure reservoir, a low pressure reservoir connected to the exhaust of said fluid motor and adapted to be connected to the intake of said compressor, the combination of means automatically injecting fluid into the intake pipe of said compressor in response to a pressure in the intake pipe of said compressor lower than a predetermined value, and a check valve in the compressor intake pipe between the low pressure reservoir and the point to the pressure o which the automatic injecting means is responsive, said check valve permitting uid to flow only in a direction from said low pressure reservoir toward said point.

4. In a closed pressure fluid transmission circuit including a compressor, a high pressure reservoir connected to the exhaust of said compressor, a reversible-valve fluid motor having an intake adapted to be connected to said high pressure reservoir, a low pressure reservoir connected to the exhaust of said uid motor and adapted to be connected to the intake of said compressor,

the combination of a chamber in the intake pipe to said compressor, means automatically injecting fluid into said chamber in response to a pressure in said chamber lower than a predetermined value, and acheck valve in said circuit between said low pressure reservoir and said chamber permitting fluid to pass from said low pressure res'- ervoir into said chamber but not to pass in the reverse direction.

5. In a closed pressure fluid transmission, circuit including a compressor, a high pressure reservoir connected to the exhaust of said compressor, a reversible-valve fluid motor having an intake adapted to be connected to said high pressure reservoir, a low pressure reservoir connected to the exhaust of said fluid motor and adapted to be connected to the intake of said compressor, the combination of means automatically injecting iiuid into the low pressure side of the circuit in response to a pressure in the compressor intake 20 jpipe lower than a predetermined value, and valve means located in said circuit between said low pressure reservoir and the intake pipe of said :compressor and adapted to prevent the automatic injecting means from operating when fluid is ex- 25 hausted from the low pressure reservoir by way of the uid motor.

i RUSSELL M. OTIS. 

